Regenerator, and heat regenerative system for fluidized gas using the regenerator

ABSTRACT

In a regenerator  1 , on the surface of a strip-shaped resin film  2 , a resin layer  3  containing an ingredient having higher thermal conductivity than the resin film  2  is formed; or, over a predetermined width from an edge of the regenerator  1 , a resin coating  4  is formed. Then, the resin film  2  is rolled into a cylindrical shape to produce the cylindrical regenerator  1 . In a flow gas heat regeneration system having the regenerator  1  disposed in a doughnut-shaped space, when a hot working gas flows into the regenerator  1  through one end thereof, the heat of the working gas is stored in the resin film  2 . Here, the resin layer  3  or resin coating  4  on the resin film  2  enhances heat conduction in the regenerator. Thus, more heat is stored in the resin film  2 . When the cold working gas flows into the regenerator  1  through the other end thereof, the heat stored in the resin film  2  is rejected to the working gas. Here, the resin layer  3  or resin coating  4  on the resin film  2  enhances heat conduction in the regenerator  1  and increases the heat capacity thereof. Thus, more heat is rejected to the working gas. In this way, it is possible to achieve high heat energy regeneration efficiency.

TECHNICAL FIELD

The present invention relates to a regenerator for use in aStirling-cycle refrigerator or the like, and relates also to a flow gasheat regeneration system employing such a regenerator.

BACKGROUND ART

A type of conventional regenerator 1 for use in a Stirling-cyclerefrigerator is, for example as shown in FIG. 8, composed of a resinfilm 2, having fine projections 2 a formed on the surface thereof,rolled into a cylindrical shape with a hollow space left inside it.

FIG. 9 is a side sectional view of an example of a free-piston-typeStirling-cycle refrigerator incorporating the regenerator 1. First, theoperation of this Stirling-cycle refrigerator will be described. Asshown in FIG. 9, the free-piston-type Stirling-cycle refrigeratorincludes a cylinder 8 having a working gas such as helium sealedtherein, a displacer 7 and a piston 5 arranged so as to divide the spaceinside the cylinder 8 into an expansion space 10 and a compression space9, a linear motor 6 for driving the piston 5 to reciprocate, a heatabsorber 14 provided on the expansion space 10 side for absorbing heatfrom outside, and a heat rejector 13 disposed on the compression space 9side for rejecting heat to outside.

In FIG. 9, reference numerals 11 and 12 represent plate springs thatsupport the displacer 7 and the piston 5, respectively, and permit themto reciprocate by resilience. Reference numeral 15 represents a heatrejecting heat exchanger, and reference numeral 16 represents a heatabsorbing heat exchanger. These heat exchangers prompt exchange of heatbetween inside and outside the refrigerator. Between the heat rejectingheat exchanger 15 and the heat absorbing heat exchanger 16, aregenerator 1 is disposed.

In this structure, when the linear motor 6 is driven, the piston 5 movesup inside the cylinder 8, compressing the working gas in the compressionspace 9. As the working gas is compressed, its temperature rises, butsimultaneously the working gas is cooled through heat exchange with theoutside air by the heat rejector 13 through the heat rejecting heatexchanger 15. Thus, isothermal compression is achieved. The working gascompressed in the compression space 9 by the piston 5 flows, underpressure, into the regenerator 1 and then into the expansion space 10.Meanwhile, the heat of the working gas is stored in the resin film 2constituting the regenerator 1, and thus the temperature of the workinggas falls.

The working gas that has flowed into the expansion space 10 is underhigh pressure, and is expanded when the displacer 7, which reciprocateswith a predetermined phase difference kept relative to the piston 5,moves down. Meanwhile, the temperature of the working gas falls, but theworking gas is heated through absorption of heat from the outside air bythe heat absorber 14 through the heat absorbing heat exchanger 16. Thus,isothermal expansion is achieved. Thereafter, the displacer 7 startsmoving up, and thus the working gas in the expansion space 10 flowsthrough the regenerator 1 back into the compression space 9. Meanwhile,the working gas receives the heat stored in the regenerator 1, and thusthe temperature of the working gas rises. This sequence of operations,called the Stirling cycle, is repeated by the reciprocating movement ofthe driven components, with the result that the heat absorber 14 absorbsheat from the outside air and gradually becomes cold.

In this way, the heat energy of the working gas is regenerated by theregenerator 1 between the compression space 9 and the expansion space10. Here, increasing the amount of heat stored in the regenerator 1results in higher heat energy regeneration efficiency. This makes itpossible to achieve an ideal Stirling cycle and thereby enhance therefrigerating performance of the Stirling-cycle refrigerator.

However, in the structure of the conventional regenerator 1 describedabove, the regenerator 1 itself is composed of a resin film 2, whichgenerally has low thermal conductivity. This leads to low heatconduction from the working gas to the resin film 2. Thus, theregenerator 1 cannot store a sufficient amount of heat, resulting inunsatisfactory heat energy regeneration efficiency. This lowers therefrigerating performance of the Stirling-cycle refrigerator. Moreover,the edges of the regenerator are prone to deformation, causingvariations in regeneration performance and leading to unstableregeneration performance. Accordingly, an object of the presentinvention is to provide a regenerator that offers excellent heat energyregeneration efficiency and stable regeneration performance.

DISCLOSURE OF THE INVENTION

To achieve the above object, according to one aspect of the presentinvention, in a regenerator composed of a strip-shaped resin film rolledinto a cylindrical shape, the resin film has a multiple layer structureat least in a portion thereof occupying a predetermined width from anedge thereof. This helps increase the strength of the edges of theregenerator so that they are less prone to deformation, and thus helpsstabilize the performance of the regenerator.

According to another aspect of the present invention, in a regeneratorcomposed of a strip-shaped resin film rolled into a cylindrical shape, alayer having higher thermal conductivity than the resin film is formedon the surface of the resin film. When the hot working gas flows intothe regenerator through one end thereof, the heat of the working gas isstored in the resin film. Here, the layer having high thermalconductivity formed on the resin film enhances heat conduction in theregenerator. Thus, more heat is stored in the resin film. When the coldworking gas flows into the regenerator through the other end thereof,the working gas receives the heat stored in the resin film. Here, thelayer having high thermal conductivity formed on the resin film enhancesheat conduction in the regenerator 1 and provides higher heat capacity.Thus, more heat is rejected to the working gas. In this way, it ispossible to achieve high heat energy regeneration efficiency.

The resin film may have a plurality of fine projections formed on thesurface thereof. This leaves gaps between different turns of the resinfilm laid on one another, and thus permits the working gas to flowthrough those gaps from the high-temperature end to the low-temperatureend and vice versa along the cylinder axis.

According to still another aspect of the present invention, in aregenerator composed of a strip-shaped resin film rolled into acylindrical shape, the resin film is composed of two strip-shaped resinfilms having a layer with higher thermal conductivity than the two resinfilms laminated between the two resin films. This helps avoid exposingthe layer having high thermal conductivity to outside.

In particular, forming the layer having high thermal conductivity on theresin film so as to occupy a predetermined with from an edge of theregenerator helps reduce the area, and thus the material costs and thelike, of the layer having high thermal conductivity compared with a casewhere the layer having high thermal conductivity is formed all over theresin film.

The layer having high thermal conductivity can be formed easily by beingprinted on the resin film as resin ink containing an ingredient havinghigh thermal conductivity. In that case, suitable as the ingredienthaving high thermal conductivity is fine particles of at least one ofgold, silver, copper, aluminum, and carbon.

By disposing the regenerator of the present invention in adoughnut-shaped space serving as a flow pass for a reciprocating gas, itis possible to realize a versatile flow gas heat regeneration systemthat offers high heat energy regeneration efficiency. In particular, byapplying the present invention to a free-piston-type Stirling-cyclerefrigerator, it is possible to achieve excellent refrigeratingperformance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing the structure of the regenerator ofa first embodiment of the invention.

FIG. 2 is an enlarged sectional view of the regenerator:

FIG. 3 is a perspective view showing the structure of the regenerator ofa second embodiment of the invention.

FIG. 4 is a perspective view showing the structure of the regenerator ofa third embodiment of the invention.

FIG. 5 is a perspective view showing the structure of the regenerator ofa fourth embodiment of the invention.

FIG. 6 is a perspective view showing the structure of the regenerator ofa fifth embodiment of the invention.

FIG. 7 is an enlarged sectional view showing the regenerator of a sixthembodiment of the invention.

FIG. 8 is a perspective view showing the structure of an example of aconventional regenerator.

FIG. 9 is a side sectional view showing an example of a free-piston-typeStirling-cycle refrigerator.

BEST MODE FOR CARRYING OUT THE INVENTION

A first embodiment of the invention will be described with reference tothe drawings. FIG. 1 is a perspective view showing the structure of theregenerator of the first embodiment of the invention, and FIG. 2 is anenlarged sectional view of the regenerator. As shown in FIG. 1, theregenerator 1 is composed of a strip-shaped resin film 2 rolled into acylindrical shape. The resin film 2 is formed out of a material havinghigh specific heat, low thermal conductivity, high heat resistance, lowmoisture absorption, and other desirable properties, suitable examplesincluding polyethylene terephthalate (PET) and polyimide.

The resin film 2 has a plurality of fine projections 2 a formedregularly all over one surface thereof. These projections 2 a can beformed, for example, by printing, embossing, or heat forming. As shownin FIG. 2, the projections 2 a permit gaps to be left between differentturns of the resin film 2 laid on one another. Thus, through these gaps,as shown in FIG. 1, the working gas flows from the high-temperature end1H to the low-temperature end 1C as indicated by an arrow A and viceversa along the cylinder axis (the direction indicated by a dash-and-dotline B).

On both surfaces of the resin film 2, resin layers 3 containing aningredient having higher thermal conductivity than the resin film 2 areformed as thin films. Suitable as the ingredient having high thermalconductivity is fine particles of gold, silver, copper, aluminum,carbon, or the like used singly or as a mixture of two or more of them.The fine particles are mixed with a resin material such as polyethylene,and the mixture is then printed, as ink, on both surfaces of the resinfilm 2 to coat it with the resin layers 3.

Next, how heat regeneration is achieved in a Stirling-cycle refrigeratoremploying this regenerator 1 will be described. When a working gascompressed and thereby heated flows into the regenerator 1 through thehigh-temperature end 1H thereof, the heat energy of the working gas isstored in the resin film 2. Here, since the resin layers 3 on the resinfilm 2 have sufficiently high thermal conductivity, the heat energyfirst conducts along the resin layers 3 and is then stored in the entireresin film 2. Thus, a sufficient amount of heat is stored. On the otherhand, when the working gas expanded and thereby cooled flows into theregenerator 1 through the low-temperature end 1C thereof, the storedheat is rejected. Here, the heat energy conducts along the resin layers3 and is rejected from the entire resin film 2 to the working gas. Thus,a sufficient amount of heat is rejected. In this way, the regenerator 1operates with enhanced regeneration energy efficiency.

A second embodiment of the invention will be described with reference tothe drawings. FIG. 3 is a perspective view showing the structure of theregenerator of the second embodiment of the invention. As shown in FIG.3, the resin film 2 has a plurality of fine projections 2 a formedregularly all over one surface thereof. These projections 2 a permitgaps to be left between different turns of the resin film 2 laid on oneanother. Thus, through these gaps, the working gas flows from thehigh-temperature end 1H to the low-temperature end 1C as indicated by anarrow A and vice versa along the cylinder axis (the direction indicatedby a dash-and-dot line B).

As shown in FIG. 3, on both surfaces of the resin film 2, resin layers 3containing an ingredient having higher thermal conductivity than theresin film 2 are formed in the shape of stripes arranged at regularintervals along the cylinder axis. In the portions on the surfaces ofthe resin film 2 where the resin layers 3 are not formed, masks are laidbeforehand in the shape of stripes arranged at regular intervals. Then,coating is performed just as in the first embodiment. Lastly, the masksare washed off and removed to obtain the resin layers 3. The stripes ofthe resin layers 3 may be arranged at irregular intervals.

Next, how heat regeneration is achieved in a Stirling-cycle refrigeratoremploying this regenerator 1 will be described. When a working gascompressed and thereby heated flows into the regenerator 1 through thehigh-temperature end 1H thereof, the heat energy of the working gas isstored in the resin film 2. Here, since the resin layers 3 on the resinfilm 2 have sufficiently high thermal conductivity, the heat energyfirst conducts to the individual stripes of the resin layers 3 and isthen stored from the individual stripes to the resin film 2. Thus, asufficient amount of heat is stored. On the other hand, when the workinggas expanded and thereby cooled flows into the regenerator 1 through thelow-temperature end 1C thereof, the stored heat is rejected. Here, theheat energy conducts from the resin film 2 to the individual stripes ofthe resin layers 3 and is then rejected to the working gas. Thus, asufficient amount of heat is rejected. In this way, the regenerator 1operates with enhanced regeneration energy efficiency.

In this embodiment, the resin layers 3 on the resin film 2 are formed inthe shape of stripes arranged at intervals. This helps reduce the lossof heat during heat conduction through the resin layers 3 from thehigh-temperature end 1H to the low-temperature end 1C. Moreover, theresin layers 3 have a smaller area than when they are formed all overthe resin film 2. This helps reduce the amount of thehigh-thermal-conductivity ingredient used, and thus helps reduce costs.Although the portions where the resin layers 3 are not formed havecomparatively low thermal conductivity, since the resin layers 3 areformed in the shape of stripes, by determining the widths and intervalsof the stripes of the resin layers 3 so that the working gas makes aslittle contact as possible with those low-thermal-conductivity portions,it is possible to minimize the lowering of heat energy regenerationefficiency.

A third embodiment of the invention will be described with reference tothe drawings. FIG. 4 is a perspective view showing the structure of theregenerator of the third embodiment of the invention. As shown in FIG.4, the resin film 2 has a plurality of fine projections 2 a formedregularly all over one surface thereof. These projections 2 a permitgaps to be left between different turns of the resin film 2 laid on oneanother. Thus, through these gaps, the working gas flows from thehigh-temperature end 1H to the low-temperature end 1C as indicated by anarrow A and vice versa along the cylinder axis (the direction indicatedby a dash-and-dot line B). Here, the portions of the regenerator 1around the high-temperature end 1H and the low-temperature end 1Cthereof contribute to heat energy regeneration to a particularly highdegree.

As shown in FIG. 4, on both surfaces of the resin film 2, resin layers 3containing an ingredient having higher thermal conductivity than theresin film 2 are formed so as to occupy a predetermined width from eachedge of the regenerator 1 by the same process as in the secondembodiment.

In this embodiment, the resin layers 3 on the resin film 2 are formed tooccupy a predetermined width from each edge of the regenerator 1, andthus have a smaller area than when they are formed all over. This helpsaccordingly reduce the amount of the high-thermal-conductivityingredient used, and thus helps reduce costs. Moreover, since theseportions of the regenerator 1 contribute to heat energy regeneration toa high degree, almost no lowering in the performance of the regenerator1 results.

A fourth embodiment of the invention will be described with reference tothe drawings. FIG. 5 is a perspective view showing the structure of theregenerator of the fourth embodiment of the invention.

As shown in FIG. 5, on both surfaces of the resin film 2, resin layers 3containing an ingredient having higher thermal conductivity than theresin film 2 are formed in the shape of stripes arranged at regularintervals along the cylinder axis so as to occupy a predetermined widthfrom each edge of the regenerator 1.

In this embodiment, the resin layers 3 on the resin film 2 are formed atintervals so as to occupy a predetermined width from each edge of theregenerator 1, and thus have a smaller area than when they are formedall over. This helps accordingly reduce the amount of thehigh-thermal-conductivity ingredient used, and thus helps reduce costs.Moreover, since these portions of the regenerator 1 contribute to heatenergy regeneration to a high degree, almost no lowering in theperformance of the regenerator 1 results.

In the embodiments described thus far, the resin film 2 is described ashaving the resin layers 3 formed on both surfaces thereof. However, itis also possible to form a resin layer only on one surface of the resinfilm. In that case, less ink is required, and coating needs to beperformed only once. This greatly reduces costs.

A fifth embodiment of the invention will be described with reference tothe drawings. FIG. 6 is a perspective view showing the structure of theregenerator of the fifth embodiment of the invention.

As shown in FIG. 6, on both surfaces of the resin film 2, resin coatings4 of polyethylene or the like are formed so as to occupy a predeterminedwidth from each edge of the regenerator 1. In the central portions onthe surfaces of the resin film 2 where the resin coatings 4 need not beformed, masks are laid beforehand. Then, a resin material is printed asink on both surfaces of the resin film 2 to achieve coating. Lastly, themasks are washed off and removed to obtain the resin coatings 4.

In this embodiment, by forming the resin coatings 4, the portions of theresin film 2 occupying a predetermined width from each edge thereof,i.e., the portions that contribute to heat energy regeneration to a highdegree, are made thicker. This not only helps increase heat storagecapacity and thereby enhance heat energy regeneration efficiency, butalso helps make the resin film 2 less prone to develop wrinkles whenrolled up.

In this embodiment, the resin film 2 is described as having the resincoatings 4 formed on both surfaces thereof. However, it is also possibleto form a resin coating only on one surface of the resin film. In thatcase, less ink is required, and coating needs to be performed only once.This greatly reduces costs.

A sixth embodiment of the invention will be described with reference tothe drawings. FIG. 7 is an enlarged sectional view showing theregenerator of the sixth embodiment of the invention. As shown in FIG.7, the regenerator 1 is composed of a composite resin film 20 rolledinto a cylindrical shape. The composite resin film 20 is composed of twostrip-shaped resin films 21 and 22 having a resin layer 3, describedlater, laminated between them. One resin film 21 has a plurality of fineprojections 2 a formed regularly all over one surface thereof. As shownin FIG. 7, these projections 2 a permit gaps to be left betweendifferent turns of the composite resin film 20 laid on one another.Thus, through these gaps, as shown in FIG. 1, the working gas flows fromthe high-temperature end 1H to the low-temperature end 1C as indicatedby an arrow A and vice versa along the cylinder axis.

On one surface of the resin film 22, a resin layer 3 having higherthermal conductivity than the resin film 22 is formed as a thin film.The two resin films 21 and 22 are laid together so that the surface ofthe resin film 22 on which the resin layer 3 is formed is kept inintimate contact with the surface of the resin film 21 on which theprojections 2 a are not formed. In this way, the composite resin film 20having the resin layer 3 laminated inside it is produced.

In this embodiment, the resin layer 3 is not exposed to outside, andtherefore it never drops off. This greatly enhances durability. In thiscase, the laminated resin layer 3 may be formed in stripes arranged atpredetermined intervals along the cylinder axis as shown in FIG. 3, ormay be formed so as to occupy a predetermined width from each edge ofthe regenerator 1 as shown in FIG. 4, or may be formed in stripesarranged at predetermined intervals along the cylinder axis so as tooccupy a predetermined width from each edge of the regenerator 1 asshown in FIG. 5.

In all the embodiments described above, the resin layer or layers 3 aredescribed as being printed as ink. However, they may be formed by anyother method, such as painting, vapor deposition, plating, orapplication of a thin film tape.

By disposing a regenerator 1 structured as described above in adoughnut-shaped space to constitute a system in which a gas is made toflow through that space in a reciprocating fashion, it is possible torealize a versatile flow gas heat regeneration system as exemplified bya free-piston-type Stirling-cycle refrigerator.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, in a regeneratorcomposed of a strip-shaped resin film rolled into a cylindrical shape,on the surface of the resin film, a layer having higher thermalconductivity than the resin film is formed, or alternatively a resincoating is formed so as to occupy a predetermined width from an edge ofthe regenerator. This increases heat conduction in the regenerator andstabilizes the performance thereof. In a flow gas heat regenerationsystem having this regenerator disposed in a doughnut-shaped space, whena hot working gas-flows into the regenerator through one end thereof,the heat of the working gas is stored in the resin film. Here, the layerhaving high thermal conductivity or the resin coating formed on theresin film enhances heat conduction in the regenerator. Thus, more heatis stored in the resin film. When the cold working gas flows into theregenerator through the other end thereof, the heat stored in the resinfilm is rejected to the working gas. Here, the layer having high thermalconductivity or the resin coating formed on the resin film enhances heatconduction in the regenerator and increases the heat capacity thereof.Thus, more heat is rejected to the working gas. In this way, it ispossible to achieve high heat energy regeneration efficiency.

In particular, when the regenerator of the present invention is appliedto a free-piston-type Stirling-cycle refrigerator, it is possible toachieve excellent refrigerating performance.

1. A regenerator comprising: a strip-shaped resin film rolled into acylindrical shape, wherein the resin film has a multiple layer structureat least in a portion thereof occupying a predetermined width from anedge thereof.
 2. A regenerator as claimed in claim 1, wherein the resinfilm has a plurality of fine projections formed on a surface thereof. 3.A regenerator as claimed in claim 1, wherein a layer used to form themultiple layer structure has higher thermal conductivity than the resinfilm.
 4. A regenerator as claimed in claim 3, wherein the layer havinghigher thermal conductivity is a resin layer containing an ingredienthaving high thermal conductivity, and the ingredient having high thermalconductivity is fine particles of at least one of gold, silver, copper,aluminum, and or carbon.
 5. A regenerator composed of a strip-shapedresin film rolled into a cylindrical shape, wherein a layer havinghigher thermal conductivity than the resin film is formed on a surfaceof the resin film.
 6. A regenerator comprising: a strip-shaped resinfilm rolled into a cylindrical shape, the resin film being composed oftwo strip-shaped resin films having a layer with higher thermalconductivity than the two resin films laminated between the two resinfilms.
 7. A flow gas heat regeneration system comprising: a regeneratoras claimed in one of claims 1 to 6 disposed in a flow path ofreciprocating gas.